1) Log into the list administrator
2) Click on "Content Filtering"
3) Choose "yes" to the question "Should Mailman filter the content of list traffic according to the settings below?"
4) Submit your changes
5) Have your techs start emailing back all the customers that complained about this and give them instructions based on steps 1-4
6) ... exhale and get up and take a walk around the building some for some fresh air